The present invention relates to a new and improved construction of an adjusting or adjustment device, particularly for articles of furniture, and especially, although not exclusively, for adjustable chairs or the like.
In its more specific aspects, the present invention relates to a new and improved construction of an adjusting or adjustment device with a lifting unit or appliance which is composed of a hydraulic cylinder and a piston or main piston equipped with a piston rod, for coupling and force impingement of two parts or components which are movable relative to one another, particularly for adjustable chairs, wherein one part is connected with the cylinder and the other part is connected with the piston rod. The main piston is loaded, on the one hand, by means of a flowable or fluent medium, and the lift or stroke of the lifting unit or appliance is adjustable by means of a control device or mechanism slidingly guided in the piston rod.
A particularly preferred field of application for adjusting devices of the type described above is represented by seats and chairs adjustable for height and inclination, as used in many different environments or areas, for example, in the office, in the home, on a ship, and in vehicles of all types. The adjusting devices are usually hydraulic cylinders, whose pistons are additionally acted upon by a force-exerting spring. For the momentary adjustment there is provided a control device or mechanism which is usually manually operated.
An adjusting or adjustment device of the aforementioned type has been disclosed by the inventor and assignee of this application in the European Published Patent Application No. 176,816 and in the aforementioned commonly assigned, copending United States application Ser. No. 06/795,500, filed Nov. 6, 1985 which is likewise employed for adjustable seats and chairs. This adjusting device possesses a cylinder and a piston with a piston rod and guide rod. In a longitudinal bore of the piston, a control piston is slidably or displaceably guided, so that channels arranged in the piston can be thereby interrupted or released. The inner volume of the cylinder is completely filled with a flowable or fluent grease or lubricant. The adjusting device is firmly positionally fixed when the channels are blocked and can move when these channels are released or freed. The use of a flowable or fluent grease or lubricant permits a very exact and unaltered maintenance of a once adjusted position.
This adjusting or adjustment device has already proven itself in practice in many fields of application. However, its use or application is limited in that the total lift or stroke of the adjusting device is relatively small and amounts to only a few centimeters, e.g. about 5 to 6 centimeters. This lift or stroke is sufficient for many applications or uses, however there are fields of application or uses, particularly for chairs, where a lift or stroke of at least about 10 cm is demanded from the adjusting or adjustment device.